Method and apparatus for opening a sealing element, which cannot be actuated, of the bottom nozzle of a casting vessel

ABSTRACT

A method of and apparatus for opening a sealing element, which cannot be actuated, of the bottom nozzle of a casting vessel, especially during continuous casting, wherein the steel which issues is passed through an immersion tube into the next steel receiver. According to the invention an oxygen infeed or lead is introduced through the hollow compartment or cavity associated with the casting jet into the region of the sealing element, the casting vessel together with the immersion tube is brought into the casting position, after introducing the steel at the beginning of casting the sealing element is lanced or burned and the oxygen infeed or lead is removed through the steel which issues from the hollow compartment or cavity associated with the casting jet.

[451 Feb. 26, 1974 United States Patent [191 Yanagida et al.

7 G l D 2 2 8/1969 Tinnes METHOD AND APPARATUS FOR OPENING 3,459,346

A SEALING ELEMENT, WHICH CANNOT 689,585 12/1901 Hartman.......... BE ACTUATED OF THE BOTTOM NOZZLE 1,833,739 11/193] Dav1s........... 3,670,799 6/1972 Vogel et al. OF A CASTING VESSEL [75] Inventors: Marco Yanagida; Susumu 0 Primary Examiner -Robert Reeves Sakanoue, I-Irdeyukr Nakagawa, all Assistant Examiner-David A. Scherbel of Kurashk" Japan; Attorney, Agent, or Firm-Werner W. Kleeman Bruderer, Feldmeilen, Switzerland Concast AG Zurich, Switzerland [73] Ass gnee. I ABSTRACT [22] Filed: Sept. 25, 1972 A method of and apparatus for opening a sealing ele- [211 PP 291,919 ment, which cannot be actuated, of the bottom nozzle of a casting vessel, especially during continuous cast- Foreign Application p n a ing, wherein the steel which issues is passed through Sept 27 197 animmersion tube into the next steel receiver. Ac-

Switzerland....................... 14059/71 cording to the invention an oxygen infeed or lead is introduced through the hollow compartment or cavity associated with the casting et into the region of the sealing element, the casting vessel together with the immersion tube is brought into the casting position,

266/34 L 822d 32/00v FieldofSearch...266/34 L, 34 LM, 42; 164/287,

after introducing the steel at the beginning of casting 1 the sealing element is lanced or burned and the oxy- 23 gen infeed or lead is removed through the steel which issues from the hollow compartment or cavity associated with the casting jet.

References Cited UNITED STATES PATENTS -673,556 Hartman..,.........;........... 22/DIG. 21 8 Claims, 2 Drawing Figures PATENTED FEB2 8 I974 SHEET 2 BF 2 METHOD AND APPARATUS FOR OPENING A SEALING ELEMENT, WHICH CANNOT BE ACTUATED, OF THE BOTTOM NOZZLE OF A CASTING VESSEL BACKGROUND OF THE INVENTION The present invention relates to a new and improved method of opening a sealing or closure element, which cannot be actuated, of the bottom nozzle of a casting vessel, especially during continuous casting, wherein the steel which issues is passed through an immersion tube into the next steel receiver, and also pertains to a new and improved apparatus for carrying out the aforesaid method.

It is known to the art prior to commencing casting to seal the bottom nozzle of steel receivers, such as, for example, ladles or tundishes, by means of a sealing element which cannot be actuated. The size of this sealing element is chosen such that after a predetermined time it is fused by the liquid metal in the casting vessel, and casting starts automatically.

It is also known to provide after the bottom nozzle of a tundish an immersion tube which leads into the next steel receiver in the form of the ingot mold. This tube is intended to protect the jet of steel which issues from the casting orifice against contact with the surrounding air.

The technique using the sealing or closure element, however, is associated with the disadvantage that in many cases, instead of its fusing, the steel above the element solidifies, thereby preventing the automatic start of casting. Lancing of this solified steel plug by means of an oxygen lance through the immersion tube is not possible since the latter is already in casting position in the ingot mold or in a second casting vessel, for example the tundish.

Lancing the botton nozzle from above by means ofa lance passed through the liquid steel in the casting vessel inmost cases does not succeed, since the nozzle only can be located with extreme difficulty and the plug in most cases extends into the casting orifice, that is to say is not accessible to the oxygen. On the contrary, the lance in most cases melts in the upper region of the bath before the plug has been removed. This process is,

however, also not favored because of its hazardous nature.

In the case of bottom nozzles with a slide closure or slide gate nozzle and sand in the outlet orifice in front of the sliding plate, the sand can sintcr together at the region of the liquid steel and offer considerable resistance to lancing with oxygen.

lf lancing from the bath side is not possible, then the casting vessel togetherwith the immersion tube must be displaced or lifted from its casting position in order to permit access by an oxygen lance to the steel plug or sand plug through the immersion tube hollow compartment or cavity. Shifting of the casting vessel from the casting position is not possible in the case of, for example, multi-strand installations with casting vessels with several casting orifices, since the orifices which are already in their casting operation would be excessively interfered with. Accordingly, the frozen-up casting orifices cannot be opened, which leads to considerable economic disadvantages. Furthermore, in the case of immersion tube orifices which issue laterally, the start of casting with the immersion tube outside its casting position is extremely dangerous because of the laterally issuing liquid steel, and for this reason also can not be carried out.

SUMMARY OF THE INVENTION Hence, from what has been discussed previously it should be apparent that this particular field of technology is still in need of an improved method of, and apparatus for, opening a sealing or closure element, which cannot be actuated, ofa bottom nozzle of a casting vessel in a manner not associated with the aforementioned drawbacks and limitations of the prior art proposals. Therefore, it is a primary object of the present invention to provide an improved method of, and apparatus for, opening such sealing element in a mannerwhich effectively and reliably fulfills the existing need in the art and is not associated with the aforementioned drawbacks and limitations of the prior art proposals.

Another and more specific object of the present invention relates to a new and improved method of, and apparatus for, lancing a sealing element without the drawback of changing the casting position of the casting vessel. A

Now in order to implement these and still further objects of the invention, which will become more readily apparent as the description proceeds, the inventive method is manifested by the features that an oxygen infeed or lead is introduced through the hollow compartment or cavity associated with the casting jet into the region of the sealing element, then the casting vessel together with the immersion tube is brought into the casting position, and after filling the steel or molten metal into the vessel and at the beginning of casting the sealing element is lanced and theoxygen infeed or lead is removed through the steel which issues from the cavity associated with the casting jet.

This arrangement makes it possible to supply oxygen to the sealing element in the casting position, whereby the process of starting casting is greatly simplified. ln multi-strand installations with a common casting vessel, for example, for eight strands, it is possible, without difficulties, to free each casting orifice at the desired point in time. These advantages permit a considerable improvement in economics since there are avoided time losses during starting of casting, and the non-operation of casting orifices as a result of freezing-up.

When using slide gate nozzles or slide closures, the method acccording to the invention provides the additional advantages that the movable slide plate is relieved of the ferrostatic pressure by the sealing element and at the same time sand is no longer necessary. As a result, the danger of the sand caking together in the nozzle or the penetration of sand particles between the plates is eliminated. When filling'and transporting the casting vessel, the slide closure is closed for increased safety, but the sealing element prevents liquid steel from coming into contact with the slide plate. At the start of casting, the slide closure can be opened without I pressure being applied to.it and without the danger of penetration of solid material into the sealing gap between the slide plates, after which the sealing element is lanced i.e., eliminated by burning.

The apparatus for carrying out the method aspects is distinguished by the features that an oxygen infeed or lead passes through the immersion tube into the region of the sealing element and that the infeed or lead, in the area where it enters the casting jet, consists of a material which can be fused or melted by the casting jet.

If the immersion tube dips under thesurface of the bath in the next steel receiver, and if the oxygen infeed or lead is introduced laterally above this bath surface into the hollow compartment or cavity associated with the casting jet, then the oxygen infeed or lead is sealed after lancing the sealing element, as a result of which liquid steel is prevented from issuing laterally through the orifice for the lead.

An advantageous solution is realized in that the oxygen infeed or lead consists of a pipe system bent in the manner of a syphon, with the end section leading from the outlet orifice or opening of the immersion nozzle, through the hollow casting compartment or cavity, into the region of the sealing element.

It is, however, also possible for the purpose of supplying oxygen to introduce a ring provided with the oxygen infeed or lead between the casting orifice and the immersion tube. This allows the end section to be introduced into the region of the charge, especially in the case of immersion tubes wherein the outlet end is of complicated shape, for example where the tubes have a large number of outlet orifices.

The end section of the oxygen infeed or lead is advantageously made of steel, as a result of which it becomes sufficiently resistant to radiant heat. Aluminium is particularly suitable for use as a material for the infeed or lead in the region where it enters the casting jet, since it easily, and without harmful effect on the cast product, can be melted by the steel which issues.

BRIEF DESCRIPTION OF THE DRAWINGS The invention will be better understood and objects other than those set forth above, will become apparent when consideration is given to the following detailed description thereof. Such description makes reference to the annexed drawings wherein:

FIG. 1 shows a section through the bottom outlet of a casting vessel with a nozzle and a subsequent immersion tube as well as the'oxygen infeed or lead; and

FIG. 2 shows a section through the bottom outlet of a casting vessel with a slide closure or slide gate nozzle and a subsequent immersion tube as well as the oxygen infeed or lead.

DETAILED DESCRIPTION OF THE INVENTION Describing now the drawings, in FIG. 1, reference rounds a casting orificeor opening 3. The nozzle 6 is followed by an immersion tube 8 which is pressed shutor sealed-off and which leads into the region of ingot mold cavity 12, an aluminium pipe 21 and an end section 20. The U-shapedaluminium pipe 21 is attached to the end of the infeed line 22 which leads into the region of the ingot mold cavity 12. This pipe 21 leads into the lower region of the immersion tube compartment or cavity 11, as shown. The end section or pipe 20, in the form of a steel pipe, is attached to the aluminium pipe 21. This end section 20 leads from the lower region of the hollow compartment or cavity. 11 to the region of the sealing element 15.

To start a continuous casting operation by means of this apparatus the oxygen infeed or lead 19 is first introduced into the immersion tube 8. Thereafter, the intermediate container or tundish is brought into the casting position, during the course of which the immersion tube 8 together with the oxygen infeed or infeed means against nozzle 6 by means of a holding device 9. This immersion tube 8 is of sufficient length that it extends from the nozzle 6 at the casting vessel A into the mold cavity 12 of for instance an ingot mold 10. The hollow compartment or cavity 11 associated with the casting jet extends from the casting orifice or opening 3 to the outlet side or end 8a of the immersion tube 8.

During preparation of the tundish a sealing element 15 which cannot be actuated is placed in the nozzle 6. This sealing element 15 consists ofa round sheet metal disc, the thickness of which is such that it is not fused or melted before casting starts, but nevertheless 19 introduced into it, assumes a pre-determined position in the ingot mold cavity 12. When this position has been reached, molten metal, typically steel is cast into the tundish until a certain level is reached. When commencing casting the non-illustrated shut-off device e.g. valve at the infeed line 22 is opened and oxygen flows at a pre-determined pressure through the oxygen infeed means 19 against the underside of the sheet metal disc 15, the temperature of which in the interim has reached a value required for lancing. The sheet metal disc I5 and any solidified steel which may lie above it is lanced, as a result of which the casting orifice or opening 3 is released. The steel which issues melts the part of the aluminium pipe 21 which lies at the region of the casting jet, as a result of which the remainder of the oxygen infeed or lead, located in the cavity 11, is removed therefrom by the steel which flows-out or issues. The remainder of the aluminium pipe 21 together with the lead 22 can thereafter be removed from the ingot mold cavity 12.

FIG. 2 illustrates a solution for a casting vessel A with' a slide closure or slide gate nozzle 25. The slide closure or slide gate nozzle 25 is fixed to the bottom 1 of the casting vessel A and its upper slide plate 26 cooperates with the nozzle 6 in the brick or block 7 which again possess a bore or hole 70. The lower slide plate 27 and the therewith associated guide 29 can be appropriately slid aside by meansof aslide actuating device 23. A spacer ring or ring member 33 is provided between the lower slide plate 27 and the immersion tube 8 provided with lateral casting orifices 8b located beneath the metal level in the mold'during the casting process. This ring 33 or ring member and the immersion tube 8' are held by means of a holder 30 against the lower slide plate 27. The holder 30 possesses a lateral orifice 30a through which the oxygen infeed means or lead 19' is passed into the spacer ring 33. The infeed line or conduit 22 here alsohas a suitable shut-off device, not shown, by means of which it can be shut-off. A short bent aluminium pipe section 21 is fixed in the bore of the spacer ring 33. A steel pipe or section 20' is mounted upon this spacer 21. This steel pipe 20 extends to below the upper slide plate 26. When starting casting with an open slide, however, it can also extend as far as below the sealing element in the casting orifice or opening 3. A further possibility, with the slide closed, is to locate the oxygen infeed means or infeed 19' in the upper slide plate 26.

With the apparatus according to H0. 2, as soon as the level of the steel in the casting vessel A has reached a certain height, then oxygen is blown into the casting orifice 3 when starting to cast. As a result the sheet metal disc 15 and, where necessary, other material impeding the melt flow is lanced. The steel which flows through melts the pipe bend 21' and the remainder of the oxygen pipe or section 20' is removed from the compartment or cavity 11, or fused, by the steel which issues or flows-out, Metal is prevented from issuing through the laterial orifice in the spacer ring 33 by closing the shut-off device in the infeed line 22.

The shut-off device in the line 22 can also be replaced by a multi-way tap. At the start of casting, oxygen is passed through the line 22. After the sheet metal disc 15 has been lanced and after the steel pipe 20 and the intermediate section 21 .have been fused and flushed out of the cavity 11, an inert gas is introduced into the infeed line 22' through re-setting the multi-way tap. This gas is under a pressure which prevents liquid steel from penetrating into the orifice which remains in the spacer ring 33 and can at the same time, during casting, serves to flush the casting orifice 3.

if the material for the end section or pipe 20' is suitably chosen the latter can be also introduced through the outlet orifice of the immersion tube 8 if this immersion tube has the shape shown in FIG. 2. This, however, requires that the end section 20 should be sufficiently malleable.

In the embodiments described, the method has been discussed in relation to continuous casting. It can, however, also be used in other processes in the manufacture of steel where there is inadequate accessability for lancing sealing elements, for example vacuum treatment, flushing with gas and the like.

While there is shown and described present preferred embodiments of the invention, it is to be distinctly understood that the, invention is not limited thereto but may be otherwise variously embodied and practiced within the scope of the following claims. Accordingly,

What is claimed is:

l. A method for opening a sealing element, of the bottom nozzle of a casting vessel, especially during continuous casting, wherein the molten metal which issues is passed as a casting jet through an immersion oxygen through the oxygen infeed in order to burn I through the sealing element after introducing molten metal into the casting vessel at the beginning of casting, and removing at least part 'of the oxygen infeed from the cavity associated with the casting jet by means of the issuing molten metal.

2. The method as defined in claim 1, including the step of placing the immersion tube to dip beneath the surface of the molten metal bath of the next molten metal receiver, placing the oxygen infeed so that the latter enters the cavity associated with the casting jet from above the surface of the molten metal bath, and sealing the oxygen infeed, following burning through of the sealing element.

3. An apparatus for opening a sealing element of the bottom nozzle of a casting vessel, comprising a casting vessel provided with a bottom nozzle, an immersion tube provided for the casting vessel through which molten metal passes into a subsequent molten metal receiver, said immersion tube having a cavity for the passage ofa casting jet, a sealing element provided for the bottom nozzle of the casting vessel, oxygen infeed means entering into said casting jet and passing to the region of the sealing element for the burning through of said sealing element, said oxygen infeed means at the region where it enters the casting jet comprises a material which can be fused by the casting jet.

4. The apparatus as defined in claim 3, wherein said oxygen infeed means comprises a flexed pipe system, said flexed pipe system having an end section leading through the cavity associated with the casting jet towards the region of the sealing element.

5. The apparatus as defined in claim 4, wherein said end section is formed of steel.

6. The apparatus as defined in claim 4, wherein the material of said oxygen infeed means at the region where it enters the casting jet is aluminium.

7. The apparatus as defined in claim 3, wherein the bottom nozzle embodies a casting orifice, a ring member interposed between said casting orifice and the immersion tube, said oxygen infeed means extending through said ring member to the region of said sealing element. I

8. The apparatus as defined -in claim 3, wherein said oxygen infeed means passes through said immersion tube to the region of said sealing element. 

1. A method for opening a sealing element, of the bottom nozzle of a casting vessel, especially during continuous casting, wherein the molten metal which issues is passed as a casting jet through an immersion tube into the next molten metal receiver, comprising the steps of introducing an oxygen infeed through a cavity associated with the casting jet into the region of the sealing element, bringing the casting vessel together with the immersion tube into casting position, feeding oxygen through the oxygen infeed in order to burn through the sealing element after introducing molten metal into the casting vessel at the beginning of casting, and removing at least part of the oxygen infeed from the cavity associated with the casting jet by means of the issuing molten metal.
 2. The method as defined in claim 1, including the step of placing the immersion tube to dip beneath the surface of the molten metal bath of the next molten metal receiver, placing the oxygen infeed so that the latter enters the cavity associated with the casting jet from above the surface of the molten metal bath, and sealing the oxygen infeed following burning through of the sealing element.
 3. An apparatus for opening a sealing element of the bottom nozzle of a casting vessel, comprising a casting vessel provided with a bottom nozzle, an immersion tube provided for the casting vessel through which molten metal passes into a subsequent molten metal receiver, said immersion tube having a cavity for the passage of a casting jet, a sealing element provided for the bottom nozzle of the casting vessel, oxygen infeed means entering into said casting jet and passing to the region of the sealing element for the burning through of said sealing element, said oxygen infeed means at the region where it enters the casting jet comprises a material which can be fused by the casting jet.
 4. The apparatus as defined in claim 3, wherein said oxygen infeed means comprises a flexed pipe system, said flexed pipe system having an end section leading through the cavity associated with the casting jet towards the region of the sealing element.
 5. The apparatus as defined in claim 4, wherein said end sectIon is formed of steel.
 6. The apparatus as defined in claim 4, wherein the material of said oxygen infeed means at the region where it enters the casting jet is aluminium.
 7. The apparatus as defined in claim 3, wherein the bottom nozzle embodies a casting orifice, a ring member interposed between said casting orifice and the immersion tube, said oxygen infeed means extending through said ring member to the region of said sealing element.
 8. The apparatus as defined in claim 3, wherein said oxygen infeed means passes through said immersion tube to the region of said sealing element. 